A conventional electrophotographic image forming apparatus (such as a later printer or digital copier) includes a fixing device that thermally fixes a developing agent image formed on a recording sheet thereto. Such conventional fixing device includes a flexible endless fusing film (or an endless belt), a heater disposed in an internal space of the fusing film, a nip plate disposed in the internal space and in sliding contact with an inner peripheral surface of the fusing film to receive radiant heat from the heater, and a pressure roller that nips the fusing film together with the nip plate to permit the endless fusing film to be circularly movable in a circumferential direction thereof.
In this fixing device, a developing agent image formed on a recording sheet is thermally fixed to the recording sheet with radiant heat from the heater while the recording sheet is nipped and conveyed between the pressure roller and the fusing film.